In recent years municipalities have found vandalism of fire hydrants an increasing problem. Such vandalism can be divided into two categories, first, unauthorized operation of the fire hydrant and, secondly, disassembly of the operating mechanism to remove brass parts and other valuable parts for re-sale of the metal.
Heretofore, efforts have been made to design tamperproof fire hydrants which required specially designed fire hydrants utilizing tools attached to the hydrant to operate the valve stems vertically against water pressure to open the hydrants or to receive a peculiarly shaped operating nut. These types of tamperproof hydrants were costly to manufacture and required municipalities to spend a great deal of money replacing existing hydrants.
A second type of tamperproof hydrant requiring extensive modification of existing fire hydrants was designed. This second type of tamperproof hydrant includes utilizing a dome shaped cap to conceal the polygonal end portion of the operating nut and leaving only limited access thereto. However, the means for rotatably retaining the dome shaped cap operatively on the polygonal end portion of the operating nut included utilizing a number of parts with one of the parts being cylindrical and fixed to the polygonal end portion against axial and rotary movement by a number of bolts and the dome shaped cap then being operatively rotatably secured thereto by utilizing a retaining ring threaded into the cap. This particular arrangement was costly and if any of the bolts subsequently backed out of the cylindrical part, they would engage against either the flange of the cap or the retaining ring preventing the cap from being freely rotatable or could lose engagement with the operating nut and thus allow the device to be removed.